Sorry I can’t reproduce the problem on my end. You want want to clear all your browser caches and check whether there is a JS error http://codex.wordpress.org/Using_Your_Browser_to_Diagnose_JavaScript_Errors
This error occurs in all browsers and on different computers. Here is what I found in Chrome’s JavaScript debug tool:
Uncaught TypeError: Cannot read property ‘parentNode’ of null
Uncaught TypeError: Cannot read property ‘hasClass’ of undefined
Yeap you might need to find the plugin that causes the error and fix or deactivate it and try WP-Polls again.
I check the JS code for WP-Polls and it doesn’t use the hasClass or parentNode property.
The plugin was incompatible with the Bind User to Category plugin.
http://wordpress.org/plugins/bind-user-to-cat/
After deactivating, it’s now working.